This invention relates generally to scintiphotography, and, more particularly, to patient restraining devices which are utilized in conjunction with the pinhole collimator and Gamma Scintillation Camera during scintiphotography.
Scintiphotography is the diagnostic technique by which both normal and diseased organs within a patient can be studied by following the passage of radioisotopes through the organ. This procedure is performed by the use of a Gamma Scintillation Camera such as Nuclear Chicago's Pho/Gamma HP camera which has the ability to visualize the entire organ of interest at one time and to follow the passage of radioisotopes through the organ. Radiation from the radioisotope is rapidly detected and the position and intensity or the gamma events are produced and displayed in a corresponding position on a cathode ray tube display. Time exposures of the gamma image can be taken thereby providing studies of the organ function in both normal and diseased states.
The Gamma Scintillation Camera System is made up of a gamma detector, assembly for supporting the detector and drive motors and controls for detector orientation. Within the gamma detector is a sodium-iodide thallium activated scintillation crystal. The control console is a desk type assembly which contains an XYZ Analyser, timer, display and power supply.
The Gamma Scintillation Camera when used in conjunction with a pinhole collimator can provide information about specific organs such as the regional function of the thyroid gland. Such single pinhole collimation is ordinarily used for thyroid imaging. In evaulation for ectopic thyroid tissue and and for imaging exceptionally large goiters, the parallel hole collimators are useful. The single pinhole collimator allows use of the whole scintillation camera field of view to image the thyroid: the closer the target is to the pinhole, the larger is the target image. A problem encountered in such scintiphotography, however is that working at close distances to the camera increases angular distortion. The single pinhole collimator is also particularly useful for obtaining oblique views of the thyroid: these show the posterior aspect of the lobe nearer the aperture without superimposing the other thyroid lobe, showing cold areas obscured by overlying or underlying functional tissue in conventional anterior views. In addition, pinhole collimation finds great utility for brain and optical scanning.
It is difficult during pinhole collimation to properly position the area under observation with respect to the scintillation camera. Although pinhole collimation allows for the scanning of hard-to-reach locations on the patient, it is difficult to perform such scanning without encountering gamma scatter.
Furthermore, the counting time required to obtain an optimal image of the emission distribution from a patient using a Gamma Scintillation Camera is determined by the amount of the radioactivity administered, sensor sensitivity, lesion uptake and contrast ratio and the ability of the patient to remain still. The longer the time required for the study, the greater is the probability that significant motion artifacts will occur. Studies show that in organ scans the motion artifacts contribute to the deterioration of the quality of the image after a certain interval of time. For example, it has been found that image quality is good up to three minutes of the scan before motion artifacts reduce the useful information that can be obtained from the increased counting rate. Thus, in order to retain high diagnostic image quality in the longer duration studies, it is critical to devise improved patient restraining techniques. Heretofore, restraining techniques were quite cumbersome in construction, uncomfortable to the patient, complicated in providing adjustability to a variety of shapes and sizes and produced gamma backscatter during the scintiphotography procedure.